plywood floor

[Jeremy]

RE: OSB is another good option as it does not delaminate like ply. It may not delaminate, but it swells & looses strength when moisture gets in. It is not stable enough to lay hard wood or tile over it (- according to the manufacturers).

As for coating the new wood, the wooden boat restorers use a 'Clear Penetrating Epoxy Sealer' to enhance the life of the wood. I read about this stuff in Don Danenberg's 'How to Restore Your Wooden Runabout'. It has been out since 1972 & has a proven history of almost doubling the life of the paint job when it is used.

If it's good enough for boats that are worth more than a new bus .  .   .    .

The top coat of rubberized undercoating is a GREAT idea!

I agree that OSB isn't suitable.

I have used the epoxy sealer stuff (SP Eposeal 300 is the brand I've used), and although it's very good it seems very expensive for what it is - I may be wrong, but it just seems to be regular epoxy thinned down with lots of solvent. If I went that route again I would look into making my own.

There is a very good single pack product called 'Universal Clear Primer', which I have known boatbuilders to use before applying any other kind or coating material (or even bonding material, which always seems a bit odd to me). UCP gives off some very interesting fumes, so use it in a well ventilated area!

Jeremy

[kyle4501]

OSB can absolutely be used as a subfloor for hardwood and tile.  OSB or Ply exposed to moisture will cause problems.  If you are going to use OSB they make a grade for exterior use.

www.osbguide.com/pdfs/SSflr.pdf

I know what the OSB manufacturers say about their 'miracle' product. I have also looked in to what contractors & suppliers of finish materials have to say about it.

I have heard the squeeks in hard wood floors laid over it & seen the cracks & poped tiles that have been laid over it. The local flooring contractors that I have talked to about this stuff have all used it & will not warranty any hardwood or tile installed over it. The OSB manufacturer won't either.

My personal experience is that it moves around a LOT. If you don't leave the propper end gap, it will cause problems. If you don't seal the cut ends, it will swell faster at the cut end. The problem is that when (not if) the wood swells form moisture, the glue to wood bond is weakened & eventually broken. Once this happens, all you are left with is a bunch of small chips of wood. When this happens with plywood, you at least have larger pieces of wood left.

YMMV

[niles500]

FWIW - My sign painter fills any voids, sands, uses Acrylic primer on BC or better plywood (full sheet) including the edges (multiple applications), Acrylic base color coat, then applies this stuff;

http://www.epoxysystems.com/acrylic.htm

I have a sign put up in 1997 that's been out in the Fla sun and rain for those ten years (never been cleaned and posts replaced 3 or 4 times due to termites and rot) and other than a little algae and dirt it looks like it could go another 10 years.

I would suggest putting felt paper on the steel members only to prevent chafing.

this may be overkill though ;-)

[Dallas]

Well Poop!

I just started replacing and dropping my floor a few weeks back and used, you guessed it, 1/2" OSB.

The first thing I did was to put multiple coats of Thompsons Water Seal on it and let it soak in for a week or two. My next step was to use Thompsons on all sides of sheets of luaun. I then clamped the sheets together with lots of 5 gallon busckets full of water to press the sheets together.

That was at the end of February. Since that time, we have moved a little over 80 miles and have already noticed swelling and uneveness. It looks as if when we get settled I'll have to replace that part I've already done.

That sux, with a great big X!

This time I'm going to use 1/2" BC and put a sheet of sealed luaun over that.

Luckily, It's only a 6' section, so I won't have that much to replace!

Dallas

[buddydawg]

For flooring applications wheter using Ply or OSB you should use 3/4" for strength.  Luaun should not be used as and underlayment especially for wood and tile.

[kyle4501]

I did a little looking (little being the key word) on the net & found this:

http://www.umass.edu/bmatwt/publications/articles/osb_vs_plywood.html

It seems to be a well ballanced article concerning the OSB vs plywood debate. The main problem for OSB is the moisture issue (retains water longer inducing rot, & the swelling issue) & it isn't recommended for use in certain areas because of this.

I feel that it is too easy for a bus to have the potential of a high humidity environment for OSB to be suitable. But OSB is a good choice for the bus barn! 

[rayshound]

Many years ago I worked for three years at Georgia Pacific particle board plant. I was an instrument tech. Anyways I used to hang out in the lab and watch the lab techs run tests each shift. They would soak it in water and it had to asorb no more than a given volume of water. They also pushed a steel ball through it and measures the force, and they would pull out a screw and measure this also. It was all interesting but bottem line it was saw dust and elmers glue by the 18 wheeler load. Sweeling and delamation was the biggest returns especially from the moble home builders. To heavy anyways.
                                                         Ray